Question For Joe Lucia on PF 52 Oil Filter

[Ed N.]

I'm attaching some pictures of a black PF 52 oil filter I have obtained from a source who got it from a person who worked for GM a long time ago.

The part number is 25012760. Were there any other cars during that time period that used a black PF 52 oil filters that perhaps this filter was made for? Or, were some black PF 52's made for Corvettes before they transitioned into a blue PF 52? The JD manual indicates that the black filters were PF 51's. This filter throws a different twist into the game. Joe, can you (or anyone else) shed some light on this. From my perspective the filter looks completely original.

[Terry M.]

Re: Question For Joe Lucia on PF 52 Oil Filter

The PF 51 filter had no anti-drain-back valve. PF 52 did. The differences are strictly internal.
The purpose of the anti-drain-back valve is to keep the filter full of oil when the filter is mounted in an other than vertical position. Since most Corvette application (And GM B-body also) is vertical no anti-drain-back valve is needed (Gen II LT1). However, these filters are used in other applications where they are not mounted in a vertical position.
If this is the filter used on the LT-5 the anti-drain-back valve would be a decided advantage -- except when changing the filter.

[Joe L.]

Re: Question For Joe Lucia on PF 52 Oil Filter

The PF 51 filter had no anti-drain-back valve. PF 52 did. The differences are strictly internal.
The purpose of the anti-drain-back valve is to keep the filter full of oil when the filter is mounted in an other than vertical position. Since most Corvette application (And GM B-body also) is vertical no anti-drain-back valve is needed (Gen II LT1). However, these filters are used in other applications where they are not mounted in a vertical position.
If this is the filter used on the LT-5 the anti-drain-back valve would be a decided advantage -- except when changing the filter.

Terry------


The LT5 engine did not use the PF-52. It used a PF-970C. It was also black, even for quite some time, in SERVICE.

[Joe L.]

Re: Question For Joe Lucia on PF 52 Oil Filter

I'm attaching some pictures of a black PF 52 oil filter I have obtained from a source who got it from a person who worked for GM a long time ago.

The part number is 25012760. Were there any other cars during that time period that used a black PF 52 oil filters that perhaps this filter was made for? Or, were some black PF 52's made for Corvettes before they transitioned into a blue PF 52? The JD manual indicates that the black filters were PF 51's. This filter throws a different twist into the game. Joe, can you (or anyone else) shed some light on this. From my perspective the filter looks completely original.

Ed-----


1992 LT1 and, perhaps, some or all 1993 LT1, used the PF-51 oil filter. Factory-installed filters were black with the silver and black label. In fact, I still have the original PF-51 filter from my 1992 LT1. Sometime in late 1992 or 1993 the PF-51 was discontinued and replaced by the PF-52 in both PRODUCTION and SERVICE. For awhile, the PF-52 used in PRODUCTION was black with the black and silver label with SERVICE examples blue. At some later time, all PF-52 filters were blue, PRODUCTION or SERVICE.

There were MANY, MANY applications for the PF-51 and PF-52 oil filters. The Corvette LT1 was, by no means, its exclusive application. Presumably, the black filters, when still used in PRODUCTION, were used for all of the GM applications utilizing the PF-51 or PF-52.

[Terry M.]

Re: Question For Joe Lucia on PF 52 Oil Filter

Terry------


The LT5 engine did not use the PF-52. It used a PF-970C. It was also black, even for quite some time, in SERVICE.

Thanks Joe. Other than the Gen II LT1 engine I am not up on these C4 details since my experience in this area is B-bodies.

[Larry E.]

Re: Question For Joe Lucia on PF 52 Oil Filter

FWIW: The below picture is THE original of off my 1994 LT1 1LE Camaro. On it now is PF35L. Larry

[Ed N.]

Re: Question For Joe Lucia on PF 52 Oil Filter

Ed-----


1992 LT1 and, perhaps, some or all 1993 LT1, used the PF-51 oil filter. Factory-installed filters were black with the silver and black label. In fact, I still have the original PF-51 filter from my 1992 LT1. Sometime in late 1992 or 1993 the PF-51 was discontinued and replaced by the PF-52 in both PRODUCTION and SERVICE. For awhile, the PF-52 used in PRODUCTION was black with the black and silver label with SERVICE examples blue. At some later time, all PF-52 filters were blue, PRODUCTION or SERVICE.

There were MANY, MANY applications for the PF-51 and PF-52 oil filters. The Corvette LT1 was, by no means, its exclusive application. Presumably, the black filters, when still used in PRODUCTION, were used for all of the GM applications utilizing the PF-51 or PF-52.

Joe thanks for responding. So would it be reasonably safe to estimate that the filter I have would be a production black PF 52 that was use in C4 Corvettes as well?

[Ed N.]

Re: Question For Joe Lucia on PF 52 Oil Filter

The PF 51 filter had no anti-drain-back valve. PF 52 did. The differences are strictly internal.
The purpose of the anti-drain-back valve is to keep the filter full of oil when the filter is mounted in an other than vertical position. Since most Corvette application (And GM B-body also) is vertical no anti-drain-back valve is needed (Gen II LT1). However, these filters are used in other applications where they are not mounted in a vertical position.
If this is the filter used on the LT-5 the anti-drain-back valve would be a decided advantage -- except when changing the filter.

Thanks for the response Terry.

[Duke W.]

Re: Question For Joe Lucia on PF 52 Oil Filter

If this is the filter used on the LT-5 the anti-drain-back valve would be a decided advantage -- except when changing the filter.

I have a couple of "upside down" filter cars, and I've found the following procedure allows the filter to be changed without spilling a drop.

First turn the filter CCW about an eighth of a turn to make sure it's not seized and can be removed. Then remove the drain plug and puncture the top of the filter. I use a big nail. This will allow a filter with or without a drain plug to empty, but give it at least five minutes, preferably more.

Install the drain plug then remove the filter. Once you can spin it by hand use your other hand to hold a rag near the botto, and once clear of the threads lift the filter while covering the bottom with the rag.

Duke

[Joe L.]

Re: Question For Joe Lucia on PF 52 Oil Filter

Joe thanks for responding. So would it be reasonably safe to estimate that the filter I have would be a production black PF 52 that was use in C4 Corvettes as well?

Ed------


Yes, but only those manufactured while this style and type (i.e PF-52) filter was in PRODUCTION use. I believe that usage began sometime in the 1993 model year. I'm not sure when it ended but by the 1996 model year I believe all PF-52 were blue.

[Joe L.]

Re: Question For Joe Lucia on PF 52 Oil Filter

FWIW: The below picture is THE original of off my 1994 LT1 1LE Camaro. On it now is PF35L. Larry

Larry------


As you picture, 1993-97 Camaro LT-1 did not use the PF-51/PF-52 filters and, instead, used the PF-25. This was accomplished simply by using a different oil filter adapter. The adapter used, except for cars with the KC4 oil cooler, was the GM #3952301, the same adapter used for all 1969-82 Corvettes and most 1984-91 Corvettes. 1984-91 Corvettes and 93-97 Camaros with KC4 oil cooler used adapter GM #10055722.

So, why did 1992-96 Corvette LT1 not use a PF-25 filter like 1993-97 Camaros? It was because the dual, close-coupled catalytic converters used on the Corvettes didn't allow satisfactory clearance between the oil filter and the left side converter. So, the smaller OD PF-51/52 was used.

[Larry E.]

Re: Question For Joe Lucia on PF 52 Oil Filter

Larry------


As you picture, 1993-97 Camaro LT-1 did not use the PF-51/PF-52 filters and, instead, used the PF-25. This was accomplished simply by using a different oil filter adapter. The adapter used, except for cars with the KC4 oil cooler, was the GM #3952301, the same adapter used for all 1969-82 Corvettes and most 1984-91 Corvettes. 1984-91 Corvettes and 93-97 Camaros with KC4 oil cooler used adapter GM #10055722.

So, why did 1992-96 Corvette LT1 not use a PF-25 filter like 1993-97 Camaros? It was because the dual, close-coupled catalytic converters used on the Corvettes didn't allow satisfactory clearance between the oil filter and the left side converter. So, the smaller OD PF-51/52 was used.

Interesting>So in essence you are indicating the LT1 that was put in the Camaro vs. Corvette had a bigger and
better Oil Filter System. Also with the Camaro using the PF25 makes it an option to use PF35L. I assume there is no
equivalent of a PF35L based on the PF51/52;Correct?? Larry

[Terry M.]

Re: Question For Joe Lucia on PF 52 Oil Filter

1994-1996 B & D bodies (Caprice, Impala SS & Fleetwood) with Gen II LT1 also used PF51/PF52 for the same reason as Corvette did.

[Joe L.]

Re: Question For Joe Lucia on PF 52 Oil Filter

Interesting>So in essence you are indicating the LT1 that was put in the Camaro vs. Corvette had a bigger and
better Oil Filter System. Also with the Camaro using the PF25 makes it an option to use PF35L. I assume there is no
equivalent of a PF35L based on the PF51/52;Correct?? Larry

Larry------


Well, the Camaro had a bigger oil filter but I would not say it was necessarily better. The Corvette applications also required the use of synthetic oil; I seem to recall that the Camaro applications did not. I think the synthetic oil requirement partially off-set the slightly lower filtering capacity of the PF-52 compared to the PF-25.

If someone wishes to install a PF-25 on a 1992-96 Corvette, it can be done. Simply remove the PF-52 adapter and install the PF-25 adapter, GM #3952301. The PF-25 will still clear the catalytic converter but it will be about 3/8" closer than the PF-52. Using a heat insulating blanket on the filter would add extra insurance. Do I recommend that anyone convert their 1992-96 Corvette LT1 to the PF-25? Absolutely NOT. It's a foolish idea.

Is there a PF-52 filter that's equivalent to the PF-35L (a synthetic media filter)? Yes, there absolutely is. It's called an AC Delco UPF-52, aka GM #25322836.

As far as filter physical size goes, the 1997-2017 LS series small blocks used in Corvettes and other GM applications use oil filters considerably smaller than a PF-52.

By the way, the PF-25 (or, PF-35) adapter GM #3952301 is "a dime a dozen", available from GM or the aftermarket. On the other hand, the PF-52 adapters, both standard and KC-4, used on 1992-96 Corvettes and a few other applications are long-since GM-discontinued, not available in the aftermarket, and very difficult to find. One doesn't want to need one.

[Pat F.]

Re: Question For Joe Lucia on PF 52 Oil Filter

Folks, from the limited research that I have conducted on this matter I have come up with the following:
The examples that I use come from original oil filters that were changed and saved. I have obtained these oil filters and they are in the oil filter vault in the basement.
I have a BLACK PF51 that came off a 1995 Corvette with a November 1994 Build Date.
I have a BLUE PF52 that came off a 1995 Corvette with a December 1994 Build Date and a Date Code of 27742, (277-Oct 4) (94-1994) (2 Maybe second shift) on the bottom of the BLUE PF52. Ken Robb provided me with this filter and the video of him taking possession of the 1995. The video shows the 1995 on a lift in the dealer's garage and the BLUE oil filter is clearly visible.
No markings on the BLACK PF51. I also have photo examples of additional BLUE PF52's , with date codes, that were present on later 1995 Corvettes.
This information as I stated is limited, but shows in slight detail that the BLACK PF51 may have been changed to the BLUE PF52 in the October-December 1994 time period.
Ed, I have a bunch of stuff for you. I have one more lead to follow.

Pat